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Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity . At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).
(at 20 °C) (face-centered cubic) (11.34 rel. to water at 4 °C) CRC ... formula weight = 222 ... "The Observed Properties of Liquid Helium at the Saturated Vapor ...
The amount of mass that can be lifted by helium in air at sea level is: (1.292 - 0.178) kg/m 3 = 1.114 kg/m 3. and the buoyant force for one m 3 of helium in air at sea level is: 1 m 3 × 1.114 kg/m 3 × 9.8 N/kg= 10.9 N. Thus hydrogen's additional buoyancy compared to helium is: 11.8 / 10.9 ≈ 1.08, or approximately 8.0%
Mahesh estimates that an MRI machine uses 10,000 liters of liquid helium over its life span. (According to GE Healthcare, a manufacturer of the machines, that life span is 12.8 years.) In 2015 ...
Water 220.64 bar, 373.8 °C [citation needed] [clarification needed] 1.968: 0.708: Kinetic energy penetrator [clarification needed] 1.9: 30: battery, Lithium–Sulfur [15] 1.80 [16] 1.26: battery, Fluoride-ion [citation needed] 1.7: 2.8: battery, Hydrogen closed cycle H fuel cell [17] 1.62: Hydrazine decomposition (as monopropellant) 1.6: 1.6
The interest stems from that accurate measurements of the unit cell volume, atomic weight and mass density of a pure crystalline solid provide a direct determination of the Avogadro constant. [3] The CODATA recommended value for the molar volume of silicon is 1.205 883 199 (60) × 10 −5 m 3 ⋅mol −1, with a relative standard uncertainty of ...
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
Helium also has a very low boiling point (-268.9°C or -452°F), allowing it to remain a gas even in super-cold environments, an important feature because many rocket fuels are stored in that ...